As described in U.S. Pat. No. 5,356,321 dated Oct. 18, 1994, the entire disclosure being incorporated herein as a written description for all purposes, an upper bearing arrangement for a turret mounted for relative rotation within the well of a vessel is shown in FIGS. 5A and 5B and described in column 11, line 57 through column 12, line 60. The bearing structure has a pair of bearing races with roller bearings positioned between the bearing races. The lower or outer bearing race is secured to the vessel, and the upper or inner bearing race is secured to the turret. The turret may tilt relative to the vessel when a load deflection occurs where, for example, the turret mooring lines on only one side of the turret are under tension. Tilting between the upper and lower races results in an edge loading of the rollers between the races. Such a misalignment of the rollers results in undesirable uneven wear and reduced life of the bearing. Tilting forces on the turret are unavoidable. Nevertheless, it is highly desirable that any tilting action between the turret and vessel be limited.
The various components of a bearing structure for a turret are relatively massive components which require that substantial manufacturing tolerances be provided to assure fitting of the various components. Out of roundness of a component requires increased tolerances. As a result, some play usually exists between associated components. A solution to the problem of increased play between massive mechanical components is needed by the mooring system art.
Prior turret systems have mounted the turret onto the axial bearing after the bearing is in place in the well of a vessel. However, due to scheduling problems during construction, the bearing might not be available to a shipyard until a time later than the turret is available. Often it is desirable to install the turret immediately. A solution is needed to the problem of prior designs which require that an axial bearing be installed on a vessel prior to installation of the turret.